System for generating a periodic scanning current



`Iuly 21, 1953 A. HAZELTINE 2,646,532

SYSTEM FOR GENERATING A PERIODIC SCANNING CURRENT Filed March 8, 1952 3Sheets-Sheet 1 INVENTOR.

ALAN HAZELTINE Zug/gdb ATTORNEY A. HAZELTINE July 21, 1953 3Sheets-Sheet 2 Filed March 8, 1952 Average Value Q i1. AF te I l T .1 1F" A ..0 a w o wooco Em. o Emtac Emtac .mo:o mocht# v9.0 @c :couw

INVENTOR. ALAN HAZELTINE m ATTORNEY A. HAZELTINE July 21, 1953 SYSTEMFOR GENERATING A PERIODIC SCANNING CURRENT 5 SheetsPSheet 3 Filed March8, 1952 FIG.5

FIG.4

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IN V EN TOR ALAN HAZELTINE Zim ATTORNEY Patented July 2l, 1953 l attestiSYSTEM FOR GENERATING A PERIODI() SCANNING CURRENT Alan Hazeltine,Maplewood, N.v J., assignor tol Hazeltine Research, Inc.,l Chicago,Ill., a corporation of Illinois Application Match s, 1952, serial No.275,601

. 21 Claims.

This invention relates to systems for generating periodic scanningcurrents for ascanning winding of a cathode-ray tube. While theinvention-v is of general application, it has particular utility asv ascanning current generating system for a television receiver. Theinvention is especially'useful in the line-frequency scanning circuit ofa television receiver and, accordingly, will be describedV in thatenvironment.`

In a television receiver which utilizes magnetic deection of theelectron beam of the cathoderay display tube thereof, it is customary topass through the line-scanning winding thereof a current of saw-toothWave form having relatively long trace intervals and relatively shortretrace intervals. A generator which develops a periodic control voltageapplies the latter to the input circuit of an amplifier that is capableof delivering relatively large amounts of energy to a load circuit whichincludes-an output transformer and the line-scanning coil of thecathode-ray tube. The foregoing generator is usually referred to in thetelevision art as a driver stage for the amplier, the latter ordinarilybeing designated' kas the line-scanning amplifier. This amplifiercustomarily employs a screen-grid type of tube, such as a tetrode,because of its high mu, its low control electrode-anode capacitance, andits large power-handling capability. The load circuit of theline-scanning amplifier is essentially inductive and includes the usualefliciency or damping diode for providing a path of reverse-current flowand for developing a so-called unidirectional boost voltage for use byother circuits of the receiver. Another unidirectional potential from asource independent of the potential developed by the efficiency diodeassociatedwith the amplifier load circuit is ordinarily applied to thescreen electrode. A second diode, or a pair of diodes, coupled to theload circuit of the amplifier by a step-up winding of the outputtransformer, may be utilized in the well-known manner to derive a highunidirectional voltage for application to an anode of the cathode-raytube.

Although prior systems for generating periodic scanning currents haveoperated satisfactorily, they are subject to certain disadvantages. Theoutput transformer in such a system is rather large and is more costlyto manufacture than is desired. Some such systems have employed outputtransformers with primary and secondary windingsr While others haveutilised autotransforrners. The last-mentioned transformers aregenerallyY somewhat smaller than the former, ,but 'still they are moreCostly and less ecient than -frequency scanning,

is desired. Applicant has determined' that some of the disadvantagespresent in both of' these types of output transformers were caused`v bythe flow of two direct currents in certain' of the winding portions ofthe transformers which created very unequal magnetomotive forcestherein. These unequal forces in turn caused direct-current saturationeffects in the transformer core. More particularly, the magnetomotiveforces created by the anode current of the tet-rode in the line-scanningamplifier greatly predominated that developed by other currents drawnfrom' the boost voltage supply, with the result that the transformercore had a considerable magnetic bias which tended to saturate the coreandi to require excessive exciting current. TheV peaks of the requiredexciting current Were reducedby the well-known practice of inserting anonmagnetic gap in the transformer core, but this gap also requiredadditional exciting current which partly defeats its purpose. Even withsuch a gap, the operating hysteresis loop of the core Will-.be largelyon one side of the flux density axis. This causes the permissible swingin the flux density to be lowered and thus requires more winding turnsfor the same applied voltage.

Another disadvantage of prior systems is of a different sort. To correctnonlinearity of linewhich would distort the picture on the display tube,it has been customary to break the continuity of the winding of theoutput autotransformer in order to insert a linearity-correctingnetwork. This entails increased cost of manufacture since the windingoperation has to be interrupted for the insertion of insulating clothbetween theY Winding portions at the break. While it has been proposedto conneet a linearity-correcting network in the supply lead to thetransformer, the proposed arrangement has not been fully effectivebecause it has not permitted the independent correction of the twosources of nonlinearity, namely the resistance of the scanning windingand the customary partial flattening of the face of the display tube,except when this flattening is very slight.

It is an object of the present invention, therefore, to provide a newand improved system for generating the scanning current for a scanningwinding of a cathode-ray tube, which system avoids one or more of theabove-mentioned disadvantages of prior such systems.

It is another object of the invention to provide anew and improvedvsystem for generating the scanning current of a scanning winding of acathode-ray tube, which system is compact and relatively inexpensive tomanufacture.

It is a further object of the invention to provide a new and improvedsystem for generating the rscanning current of a scanning Winding of acathode-ray tube, which system is economical of power.

ing system by the use of only the same apparatus that is needed toachieve the purpose stated in the preceding paragraph.

Inv accordance with a particular form of the invention, a system forgenerating a periodic scanning current for a scanning Winding of acathode-ray tube comprises a primarily inductive load circuit includinga transformer having a magnetic core and a plurality of winding portionsand including a circuit for coupling a scanning winding thereto. Thesystem also includes an electron-discharge device having inputelectrodes and having output electrodes coupled to the load circuitthrough a first of the winding portions, and a circuit for applying tothe aforesaid input electrodes a control voltage for periodicallyrendering the device conductive to develop the scanning current in ascanning Winding coupled thereto. The generating system further includesa circuit including a rectier device and a second of the windingportions and cooperating with the electron-discharge device to carry atleast a portion of the scanning current. The system additionallyincludes a circuit including a unidirectional voltage source, asubstantial. alternatingcurrent impedance, and a third of the windingportions for supplying a direct component of current Which includes thedirect component of current of the output electrodes. The rst windingportion is at least in part distinct from the third winding portion, andthe product of the effective number of turns of the third windingportion and the first-mentioned direct component of current isapproximately equal to the product of the effective number rof turns ofthe first Winding portion and the direct component of output electrodecurrent. The aforesaid third winding portion is wound and connected insuch sense relative to the first winding portion that the directcomponents `of current have opposite directions relative to the magneticcore.

Also in accordance with the present invention, a system for generating aperiodic scanning current for a scanning Winding of a cathode-ray tubecomprises a primarily inductive load circuit including anautotransformer having a magnetic core and a series of winding terminalsand including a circuit for coupling a scanning winding to two of saidterminals. The generating system also includes an electron-dischargedevice, having input electrodes and having output electrodes includingan anode, coupled to the load circuit through a rst and a second of theterminals, with the anode connected to the second terminal. The systemfurther includes a circuit for applying to the input electrodes acontrol voltage for periodically rendering the del/ice QQnduC/V? '90develop the scanning current in a scanning Winding coupled thereto, anda circuit including a unidirectional voltage source, a rectier deviceand a low-impedance condenser coupled to a third of the terminalsintermediate the first and the second terminals and cooperating with theelectron-discharge device to carry at least a portion Iof said scanningcurrent. The generating system additionally includes a circuit includingthe aforesaid unidirectional voltage source, the rectifier device, and asubstantial alternating-current impedance coupled to a fourth of theterminals intermediate the secondA and the third terminals for supplyinga direct component of current which includes the direct component ofcurrent of the n output electrodes. Y

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a circuit diagram, partlyschematic, of a complete television receiver including a system forgenerating a scanning current for a scanning Winding of a cathode-raytube in accordance with a particular form of the present invention;Figs. 2-5, inclusive, are graphs utilized in explaining the operation ofthe generating system of the Fig. 1 receiver; and Fig. 6 is a circuitdiagram of a modified form of the invention.

Referring now more particularly to Fig. 1 of the drawings, thetelevision receiver there represented comprises a receiver of thesuperheterof dyne type including an antenna system 18,'II coupled to aradio-frequency amplifier I2 of-one or more stages. There is coupled tothe latter unit in cascade, in the order named, an oscillatormodulatorI3, an intermediate-frequency amplier I4 of one or more stages, adetector and automatic-gain-control or AG. C. supply l5, aVideofrequency amplifier It of one or more stages, and a cathode-raytube image-reproducing device I1 of conventional construction providedwith the usual line-frequency and field-frequency scanning windings Iand I9, respectively, for deflecting the cathode-rayY beam in twodirections normal to each other. The A. G. C. supply circuit I5 isconnected to the input circuits of one or more of the stages I2, I3'andI4 by a control circuit conductor 29. Connected to output terminals ofthe intermediate-frequency amplier I4 is a conventionalsound-reproducing system Z which comprises the usual soundintermediate-frequency ampliier, frequency detector, audio-frequencyamplifier, and a loudspeaker.

'I'he output circuit of the video-frequency amplifier I6 is coupled tothe input circuit of a linefrequency control generator 23 and a field-Yfrequency generator 24 through a synchronizingsignal amplier andseparator 2l and an intersynchronizing-signal separator 22. The outputcircuit of the field-frequency generator 2d is coupled to inputterminals 10, 15 in the input circuit of a repeater or ampliiier 26including an electron tube 21 having its anode circuit coupled to theheld-scanning winding I9 of the imagereproducing device II through atransformer 2B. The output circuit of the control generator 23 iscoupled to the line-scanning winding I8 through terminals 4U, d0 and 31,3'I coupled to circuits of a generating system 25 constructed inaccordance With the present invention, which generating systemeffectively comprises the line-frequency aci/ideas generator for thetelevision receiver. Anode excitation. potential for the-second anode ofthe image-reproducing device II is. supplied to a terminal 80 thereoffrom the generating system 2b. The unit Ill-25, inclusive, with theexception of. the: generating system 25, which is constructed inaccordance with the present invention and will be described in detailhereinafter, may be of conventional construction andv operation so thata detailed description and explanation of the operation thereof areunnecessary herein.

Considering briefiy, however, the general operation oftheabove-described receiver as a whole, signals intercepted by therantennasystem it, I i areselected and amplified in the radio-frequencyamplifier I2 and are. supplied to the oscillatormodulator I3 whereinthey are converted into intermediate-frequency signals. The latter, inturn, are selectively amplified in the intermediate-frequency amplifierHi and are delivered to the detector and automatic-gain-control supplyI5. The modulation components of the signalY are derived by the detectorof unit I5 and are supplied to the video-frequency amplifier I6 whereinthey are then amplified and supplied to the input circuit of theimage-reproducing device I1. A control voltage derived by theautomaticgain-control' supply of unit I5 is applied by the controlcircuit conductor 2S as an automaticamplification-control bias to thegain-control icircuits of units I2, I3 and It to maintain the signalinput to the detector of unit I5 within a relatively narrow range for awide range of received signal intensities.

Unit 2! separates the 'synchronizing signals from the other modulationcomponents of the composite video-frequency signal applied thereto fromthe video-frequency ampliiier it. The line-synchronizing andfield-synchronizing signals derived by the separator 2! are separatedfrom each other by unit 22 and are then supplied to respective ones ofthe generators 23 and 24 to synchronize the operation thereof. Unit 23develops a periodic control voltage for application to the generatingsystem 25 to control the operation thereof. An electron beam is producedby the cathode-ray image-reproducing device I'i and the intensity ofthis beam is controlled in accordance with the video-frequency andcontrol voltages impressed on the brilliancycontrol electrode from thevideo-frequency amplifier i6. Sawtooth current waves generated in theline-frequency generating system 25 and Valso in the field-frequencygenerating system including the generator 2t and the amplifier 25 areapplied to the scanning windings of the unit Il to produce scanningfields, thereby to deflect the cathode-ray beam of that unit in twodirectionsl lDescription of generating system 25 of Fig. 1

Referring now more particularly to the portion of the Fig. l receiverembodying the present invention, the system for generating a periodicscanning. current'ior the line-scanning winding y I3: of the cathode-rayimage-reproducing device.

Il comprises. a primarily inductive load circuit including anautotransformeri having a magnetic. core St and a continuous winding.including a plurality of windingsections 3i, 32, 33, tilk and 3.5, thenrst four of' these winding sections `cornprising a first windingportion of the transformer, and including a circuit for vcoupling.; the

winding it to the first-mentioned one of the winding sections. g Thislast-mentionedcircuit includes the electrical connetcions 36, 36connected to the extremities of the winding section 3 t and a lpair ofterminals 31,' 3l' connected to the line-scanning winding i8. Theautotransformer tilpreferably is of theytype described and claimed inapplicants copending application Serial No. 275,603, filed concurrentlyherewith and entitled Autotransforiner for Scanning System' ofTelevision Receiver. The.' generating system 25 also includes anelectron-discharge device suchlas a tetrode tt having controlelectrode-cathode inputv electrodes, anode-cathode output electrodeseffectively coupled to the load circuit, and a screen electrodeintermediate the output electrodes. The Liunction of thewinding sections3d and: 35 is connected directly ,to the anode of the tube it, and theextremity of the winding section 3E remote from the aforesaid junctioniscou-pled to the grounded cathode of the tube through an energy-storagedevice or. condenser 39 ofk low impedance.V

rihe system t5 also includes a circuit for applying to the inputelectrodes of the'tube t a control voltage for periodically renderingthat tube conductive to develop a scanning current in the winding i8`when itis cou-pled in circuit in the manner represented. Thecontrol-voltage applying circuit includes the pair of terminals lit, t@coupled to the output circuit of the generator 23 andcoupled to theinput electrodes of the tube 3B through a coupling' condenser di and agrid-leak resistor 42.

The generating system 25 further includes a circuit including a rectierdevice and a. lsecond of the winding portions and cooperating with thetube 38 to carry at least a portion 'of the scanning current ofline-scanning winding I8. This circuit comprises a. voltage-generatingcircuit including in series relation a unidirectional voltage source-l-B, a rectifier device fili having its anode connected to the sourcejust mentioned, a highly capacitive impedance comprising a condenser l5connected tothe cathode of the diode, a second winding portioncomprising winding sections .32 and .ti of the transformer 3u forcarrying at least a portion of the scanning current, and the condenser39 for developing a unidirectional voltage across the condenser 39-substan-tially higher than the source -l-B.

The generating system 25 additionally include a direct-currentoutputcircuit connected to the described voltage-generating circuit, namely,across condenser 39 of that circuit. This circuit preferably comprisesthe series combination of the decoupling resistor il connected to the`junction of the winding section 3i and the condenser 39, the primarywinding of the transformer 28 which is in turn connected to the anode ofthe tube 2l, the space-current path of the tube 2l, an adjustablecathode resistor i9 for that tube, and the screen electrode-cathode pathof the tube 38. A generati-ng system including the series combinationreferred to above is more fully described and claimed in applicantscopending ap- 7 plication Serial No. 275,602, led concurrently herewithand entitled "System for Generating Scanning Currents. The outputcircuit under consideration also includes a pair of terminals 9|, 9| forsupplying energy to suitable other direct-current circuits (not shown)of the tele- Vision receiver requiring such energy. By-pass condensers48 and 5I serve to decouple the fieldscanning and line-scanning systems.

Since the line-scanning coil I8 is in parallel with winding section 3|,direct current flowing through the direct-current output circuitris inpart diverted from winding section 3 I by the linescanning coil. Inconsidering the magnetic bias of the transformer core, such divertedcurrent is equivalent to a reduction in the number of turns of windingsection 3 I, leaving an effective number of turns equal to the actualnumber multiplied by the ratio of the resistance of the line-scam ningwinding to the sum of the resistances of the line-scanning winding andwinding section 3i.

l The expression effective number of turns as used hereinafter refers tothe actual number of turns of all other winding sections and'to thenumber of turns of winding section 3I multiplied by the ratio juststated.

The system 25 for generating a periodic scanningvcurrent also includesthe source hl-B, the rectifier device 44, a substantialalternatingcurrent impedance which preferably is a highly inductiveimpedance or inductor 43, and a third winding portion comprising thewinding sections 33, 32 and-SI for supplying through the inductor 43 adirect component of current which includes the direct component ofcurrent translated by the winding section 34 to the output electrodes ofthe tube 33. The product of the total effective number of turns of thethird winding portion (comprising the winding sections 33, 32 and 3|)and the first-mentioned direct component of current (that is, the directcomponent flowing through the inductor 43) is approximately equal to theproduct of the total effective number of turns of the first windingportion (comprising the winding sections 34, 33, 32 and 3l) and thedirect component of output electrode current of the tube 33 which flowsin the winding section 34. In practical embodiments f the invention, the

' first-mentioned product may be a substantial fraction of or within therange of 0.9 to 1 times the second-mentioned product. In a particularembodiment of the invention, the products, taken in the order mentionedabove have a ratio of substantially 0.98. The third winding portion ofthe transformer 33 is wound and connected in such sense relative to thefirst winding portion that the direct components of current in thetransformer have opposite directions relative to the magnetic core 93.It will be observed that the rst winding .portion is at least in partdistinct from and has a greater number of turns than the third windingportion. Also the third winding portion has a greater number of turnsthan the second winding portion.

The condenser 43 and the inductor i3 are preferably so proportioned thatcurrent flowing in the condenser builds up across the condenser avoltage which is impressed on the line-scaning winding I8 aftertransformation and which at least in part compensates for thenonlinearity in the scanning of the cathode-ray image-reproducing deviceI1.

The load circuit of the generating system 25 also includes ahigh-voltage rectifier system such as a conventional voltage-doublercircuit 55 in- 51. gether through a condenser 54 and are also connectedto'one extremity of the step-up windingY section 35 of the transformer30. Auxiliary transformer windings 58 and 59 supply heaterv current tothe filaments for the cathodes of the`v diodes 56 and 51 and the cathodeof the .latter is connected to ground through a storage condenser 50.The anode of the diode 53 is connected tothe cathode-of the diode 51through a resistor EI. The cathode of the diode 55 is connected to thecathode of the diode 51 through a storage condenserr and to the anodeterminal of the image-reproducing device I1 through a protectiveresistor 63 in an output terminal 34.

Explanation of operationV of generating system 25 of Fig. .1

In considering the general operation of 'the generating system 25 ofFig. l, it will be assumed initially that the system has been inoperationV for a brief interval of time to establish a cutoff bias onthe control electrode of the tube 38 and operating potentials across thevarious other portions of the system such as the storage'condenser 39.Curve A of Fig. 2 represents the periodic voltage applied to the inputcircuit of tube' 33 from the generator 23, the first intervals trl-t1representing Vthe latter portion ofV a trace interval. During theinterval iii-ft2,

hereinafter referred to as a retrace interval, the

mences to increase gradually to Zero, thus form-- ing a succeeding traceinterval.

At time to the periodic voltage applied to the control electrode of thetube 38 exceeds its cutoff level and anode current begins to flow in thetube and increases in the manner represented by curve B. At this timethe diode 44 is also conducting rather heavily and the diode current hasthe wave form represented by curve C. The current owing in theline-scanning winding I8 effectively constitutes the algebraic sum ofthe alternating components of current flowing in the diode d4 and in theoutput circuit ofthe tetrode 33, each current being reduced tothe'number of turns in winding portion 3|. This resultant current has asubstantially saw-tooth wave form as represented by curve D of Fig. 2.At time t1,

the negative pulse portion ofthe periodic voltage of curve A applied tothe control electrode of the tube 38 drives the tube to anode-currentcutoff. As a result of this rsudden interruption of anode current,thecmagnetic fields in the essentially inductive load circuit comprisingthe transformer 30 and the line-scanning winding I8 collapse and thedistributed and' other cir` cuit capacitances of the load circuitypermit free oscillations to take place, the free oscillation frequencybeing from three to four times that of the line-scanning frequency. vAsa result of the collapse of the magnetic field in the transformer 30, apositive voltage pulse havingV a nearly sinusoidal rise is momentarilyinduced at the various terminals of the winding above the junction ofthe condenser 39 and the resistor 41. 'Ihe positive potential applied tothecath- During the succeedingY 9. ode of the diode i4 exceeds that ofthe source +B .and renders the diode non-conductive at substantially thestart of the retrace interval ril-t2 as represented in curve C. Duringthis interval, the current iiowing in the line-scanning lwinding i8decreases rapidly from a positive.

value to zero'and then swings negative as shown by curve D. Thereversal-of the current flow in the line-scanning winding during theretrace interval t1-t2 causes the `electron beam to be deflected quicklyin a direction opposite to that during the preceding trace interval. Thedescribed retrace operation occurs in siightlymore than one-half thecycle of the free loscillation frequency of the load circuit.

Whenthe trailincr edge of the positive voltage pulse developed at thejunction Aof the Winding sections 32and 33, and hence effectively at thecathode of the diode te as a result of the translation of that pulse bythe condenser d5, drops at approximately time t2 to a value less thanthat of the source +B applied to the anode as in curveE, the diode againbecomes conductive and initiates the start of the trace interval t2'-t3.The current in the line-scanning winding IS at the start of this retraceinterval is negative and begins to decrease approximately linearly inthe manner represented by curve D.

The diode current flowing during the initial portion of the traceinterval t2-t3 is also effective to supply energy to the storagecondenser 39 and the latter assumes an average potential substantiallygreater than that of the source +B, this potential being represented bythe broken-line curve El of Fig.. 2. Early in the trace interval lf2-t3,the Vpotential of curve A applied to the control electrode of the tube33 is again effective to overcome the bias thereon and render that tubeconductive. During the remainder of the trace interval, the currentsflowing in the diode f' and the tube 38 develop a positive-goingapproXima-tely linear portion of the line-scanning current representedby curve D for deflecting the cathode-ray beam of the device ll in theWellknown manner. At time t3 the negative pulse applied to the controlelectrode of the tube 3% suddenly renders the tube nonconductive, andduring the retrace interval t3-t4 the cycle of operation explained abovein connection with the retrace interval t1-t2 is repeated.

During retrace intervals such as ti-tz and lf3-t4, large positivevoltage pulses of the type represented by curve E are developed at thejunction of the voltage step-up winding section 35 and the anode of thediode 5l in the manner previously explained. The diodes and 5l of thevoltage-doubler circuit 55 rectify these pulses in the Well-known mannerand derive across the condensers Bt and S2 a high unidirectional voltagewhich is delivered through the resistor 63 to the terminal 613 forapplication through the terminal 8f3 to an anode of theimage-reproducing device l1.

As previously mentioned, there is developed across the condenser 39 anaverage unidirectional potential of positive polarity which issubstantially greater than that of the source +B, this voltage beingusually about twice that of the source. The tube 38 requires a screenpotential much lower than that developed across the condenser 38 and theproper operating potential therefor is derived by the circuit comprisingthe voltage-dropping resistor the tube 2l, and the resistor 49 in themanner fully explained `10 Vin applicants .above-mentioned copendingplication Serial No. 275,602.

Considering now the manner in -which -the magnetic bias developed in thetransformer core is reduced to effect the improved voltage-generatingsystem k25 in accordance with the present invention, the autotransformer-translates two direct components vof current in opposite directions incertain of the winding portions thereof. The rst of these components isthe direct component of anode lcurrent for the 'tube 38 and this isconducted `in what may 'be referredto for convenience as being in theupward -direction by the winding 34. The other of these componentsofydirect current is that conducted in what may also be referred to forconvenience.

as being in the downward direction by the series combination of thewinding sections 33, 32 and 3i, the winding section 3| having `a reducednumber of effective turns by reason of fthe direct current diverted fromit by the line-'scanning windingv i8', as described previously. Thelast-mentioned direct component of current represents that supplied toany direct-current circuit connected to the terminals '9|,g'9i and the.circuit including the resistor 41, the tube 2,- and the cathode resistor49 supplying screen-electrode current to the tube 38. I-n priorgenerating systems of the type under consideration, the magnetomotiveforce developed by the flow in the transformer of the direct -componentfof-the? tetrode anode current greatly predominated the magnetomotiveforce developed by the ow of y the direct component Vof current into thesocalled boost condenser corresponding to the condenser 39. Thisundesirably causedthe transforrner core to have a considerable magneticbias which tended to produce a direct-current saturation of the core.Fig. 3 represents the hysteresis loop for a transformer which isoperated under such conditions and it will be seen therefrom that theoperation is'almost entirely on one side of the magnetic `flux densityaxis, `thus lowering the permissible swing in flux density and requiringmore winding 'turns to develop the same voltage.

As previously mentioned, the diode M translates for application to thetransformer 30 a current having the wave form represented by curve C ofFig. 2. This current contains a direct component which, in accordancewith the present invention, is effectively translated by the inductor133 and is represented graphically in Fig. 2 by the curve C. Also inaccordance with the invention, the alternating component represented bycurve C is translated by the condenser and is employed to supply aportion of the saw-tooth current in the scanning winding I8. The averageor direct component of tetrode current is represented by curve B of Fig.2 and the direct component of current (not shown) supplied to thevoltage-dropping and screen-electrode circuit of tube 38 and to thecircuit connected to the terminals 9|, Bl'is equal to the differencebetween the direct component of diode current and the direct componentof the anode current of the tetrode. By employing the inductor i3 toconduct mainly the direct component of diode current and the condenser45 be effected, thereby substantially reducing or effectivelyeliminating the undesired direct-current saturation of the transformercore.

In the Fig. 1 embodiment of the invention, this substantial reduction ofthe direct-current bias of the transformer core occurs when the variouscircuits are connected to the transformer 36v as represented and whenthe product of the total effective number of turns of theabove-mentioned third winding portion comprising the winding sections33, 32 and 3| and the directcurrent component of thecurrent throughdiode 44 and inductor 43 is approximately equal to that produced by theproduct of the eective number of turns of the first winding portioncomprising sections 34, 33, 32 and 3i by the direct component of anodecurrent of the tube 38.

A satisfactory working balance of the directcurrent magnetomotive forcesin the transformer 30 results when the first of these products is Withinthe range of 0.9 to 1 times the second of the products. For such acondition, Fig. a represents the hysteresis loop for the transformer 3U.It will be seen from this figure that the magnetic flux density Bn inthe weaker direction isa substantial fraction of the maximum fluxvdensity Bm in the other direction. This results in a range of fluxdensity nearly twice that available in a transformer having a hysteresisloop such as that of Fig. 3. netic balance is achieved, the hysteresisloop for the transformer 30 appears as represented in Fig. 5 of thedrawings and the fundamental operation of the transformer is then notaffected by the direct components of current in the various portions ofthe autotransformer. The realization of a satisfactory working balanceof the direct-current magnetomotive forces in` the transformer permitsthe use of a negligible nonmagnetic air gap in the transformer core,reduces the size of the transformer core and the exciting currentrequired to operate the transformer, and allows the use of fewer turnsfor a desired voltage, thus permitting the transformer to be smaller andless costly.

There are advantages in connecting inductor ,43 to such a pointY in thetransformer winding of Fig. l that the winding section 3,3. hasV fewerturns than would give an exact magnetic balance. First, theself-inductance of inductor i3 can then be made lower, thus lowering itscost and tending to lower its resistance and the power loss in thisresistance. Second, the alternating-current load Iof inductor d3 on thesystem can be made lower, even with a lowered self -inductance It shouldbe pointed out that substantial reduction in magnetic bias isaccomplished in the circuit of Fig. l, not only by magnetic balance asdescribed previously, but also by the lowering of the number of turnsthrough which flows thedirect component of anode current of the tube 38,

Y sections 33, 32 and 3 i.

As is well known, the picture reproduced on the display tube of atelevision receiver is subject to distortion in a horizontal direction,such distortion being commonly referred to as nonlinearity with respectto time of the horizontal displacement of the bright spot produced onthe When an exact magby curve Cin Fig. 2.

screen by the moving electron beam. This nonlinearity is due to twoindependent effects: (l) the resistances of the scanning winding, ofparts of the output transformer winding, and of the diode rectifier,which tend to cause the reproduced picture t0 be relatively spread outnear the beginning of yeach line and condensed near the fects, there areinserted effectively' in series withY the scanning winding a voltagewhich varies linearly with time to correct the rst effect and a voltagewhich varies parabolically with time to correct the second effect. f

In accordance with the present invention, both of these correctingvoltages are inserted across the condenser 45 of Fig. 1 `by alternatingcomponents of current owing through this condenser. The linearly varyingvoltage is Vproduced by a component of current which is of rectangularwave form and has a constant value in one direction during the traceinterval and a much higher valueV in `the other direction during theshorter retrace interval. current is supplied by the rectier diode 44,whose total current flows in one direction throughout trace andisinterrupted during retrace, as shown The total change in the linearlyvarying voltage during trace is, in fact, nearly equal to the directcomponent of rectifier current multiplied by the retrace time anddivided by the capacitance of condenser 45, and this relation determinesthe required capacitance.

The parabolic correcting voltage required for flat-face correction isproduced by a component of current through condenser l5 having asawt-ooth wave form, like the current of the scanning winding, as shownby curve D in Fig. 2. The current of the rectifier diode 4 contains sucha sawtoothccmponent of current, but of quite insufficient magnitude, sothe greater part of the required saw-tooth component is obtained fromthe alternating component of current owing through inductor i3 of Fig.l, which current is of nearly saw-tooth form because (like the currentof the scanning winding) it is due to the voltage of a portion of thetransformer winding, the voltage across condenser A5 being relativelysmall. Thus, the required parabolic component of correcting voltagedetermines the self-inductance of inductor 43, other relevant factorsbeing already xed by other considerations.

From the three preceding paragraphs, it will be seen that the systemshown in Fig. 1 serves not only to reduce or'eliminate the deleteriouseffect of magnetic bias in the transformer core, as describedpreviously, but also for linearity correction, merely by suitable choiceof the capacitance of condenser G5 and the self-inductance of inductorQ3, without the necessity of adding vany parts. Of course, the systemcan be advantageously used for linearity correction alone, in caseswhere magnetic bias may not constitute a problem.

ed form of the invention which is essentially Y similar to thegenerating system of Fig. l, similar circuit elements being designatedby the same Such a component of 13 reference numerals and analogouscircuitelements by the same reference numerals with the subscript a. Thegenerating system of Fig. 6 diiers from that of Fig. 1 in that thetransformer 30a is not an autotransformer but'goes to the oppositeextreme of maintaining the winding portions distinct from each other.The rst winding portion Ziria is connected between the anode of thetube-3B and the high-potential terminal of the condenser 39. A secondwinding portion 32a is coupled between the aforesaid terminal ofcondenser 39 and the cathode of the diode E through the condenser 5. Athird winding portion 33a is coupled between the high-potential terminalof the condenser 39 and the cathode ofthe diode is through the inductor43. The line-scanning winding I8 is coupled to the winding section Slawhich is in turn inductively coupled to the other winding portions. Theproduct of the number of turns of vthe third winding portion 33a and thedirect component of current translated through the inductoi` i3 isapproximately equal to the product of the number of turns of the firstwinding portion 3fm: and the direct component of output electrodecurrent of the tube 38. The third Winding portion 33a is wound andconnected in such sense relative to the iirst winding portion 36a thatthe direct components of'c'urrent in the transformer have oppositedirections relative to the magnetic core QG. The operation of the Fig. 6generating system 25a, is essentially similar to that of the generatingsystem of Fig. 1 and, therefore, will not be repeated.

The following circuit constants are given as illustrative values ofcircuitY elements whichmay be used in the generating system 25 cf Fig.i:

Tube 27 Type SSN? Tube 38 Type 6BQ6-G Tube 44 Type GVB Resistor 49 470kilohms Resistor 47 lkilohm Resistor 49 1 kilohm (max.)

Condenser 39 Condenser 41 Condenser 45 Condenser 48 Condenser 5lTransformer 30,

single coil with #34 single silk enamel wire and the following numbersof turns Winding portion 31.. Winding portion 32 100 turns Windingportions Q3, 34 Each 80 turns Y Winding portion 240 turns Inductor 43 30millihenries Winding 18 13.3 millihenries B 220 volts 100 voltspeak-to-peak 130 volts average 8 microfarads 0.01 mi'crofarad 0.022microfarad 50 microfarads 10 microfarads 200 turns Input voltage to tube38 Screen-electrode voltage to tube Line-scanning frequency Directcomponent of current in inductor 43. Direct component of anode currentof tube 38. Direct component of current in boost load circuits.

Vskilled in the art that various changes and modications may be madetherein without departing from the invention, and it is, therefore,aimed to cover all such changes and modiiications as fall Within thetrue spirit and scope of th'e invention.

What is claimed is: l. A systemVV i'or generating a periodicscanning-current :fora Vscanning lwinding ofa 'cathoderay tubecomprising: a primarily inductive load circuit including anautotransformer having a magnetic core and a plurality of Windingportions and including a circuit for coupling a scanning windingthereto; an energy-storage device; an electron ytube having controlelectrcdeecath'ode input electrodes and having anode-cathode outputelectrodes vcoupled. to said load circuit through a series circuitincluding a rst of said winding portions and said energy-storage device;a rcircuit for applying to said input electrodes `a control'voltage forperiodically rendering said tube conductive to develop said scanningcurrent in a scanning winding coupled thereto;` a voltage'- generatingcircuit including said energy-storage device, a unidirectional voltagesource, a rectifier device, a lou/impedance condenser, and a second ofsaid winding portions and cooperating with said tube to carry at least aportion of said scanning current and to develop across saidenergystorage device a unidirectional voltage substantially higher thanthat of said source; a directcurrent output circuit connected to saidenergy'- storage device; and a circuit including said unidirectionalvoltage source, said rectifier device, an inductor, and a third of saidwinding portions having a greater number of turns than said secondwinding portion for supplying a direct component of current whichincludes the direct com'- ponent of current of said output electrodes;said rlrst winding portion being at least in part distinct from saidthird winding portion and the product of the effective number of turnsof said third winding portion and said rstementioned direct component ofcurrent being approximately equal to the product of the effective numberof turns of said rst winding portion and'said direct component of outputelectrode current, and said third winding portion being wound and con*-nected in such sense relative to said rst winding portion that saiddirect components of current have opposite directions relative to saidmagnetic core.

2. A system for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: arprimarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof winding portions and including a circuit for coupling a scanningwinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through aiirst of said winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning windingcoupled thereto; a circuit'including a rectier .device and a second ofsaid winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; andacircuit including a unidirectional voltage source, a substantialalternating-current impedance, and a third of said winding portionscircuit including a transformer having a magnetic core and a pluralityof winding portions and including a scanning Winding coupled thereto; anelectron-discharge device having input electrodes and having outputelectrodes coupled to said load circuit through a rst of said windingportions; a circuit for applying to said input electrodes a controlvoltage for periodicallyrendering said device conductive to develop saidscanning current in said scanning Winding; a circuit including a rectierdevice and a second of said Winding portions and cooperating with saidVelectron-discharge device to carry at least a portion of said scanningcurrent; and a circuit including a unidirectional voltage source, asubstantial alterhating-current impedance, and a third of said Windingportions for supplying a direct component of current which includes thedirect component of current of said output electrodes; said rst Windingportion being at least in part distinct from said third winding portionand the product of the elective number of turns of said third Windingportion and said first-mentioned direct component of current beingapproximately equal to the product of the effective number of turns ofsaid rst Winding portion and said direct component of output electrodecurrent, and said third Winding portion being Wound and connected insuch sense relative to said rst winding portion that said directcomponents of current have opposite directions relative to said magneticcore.

fl. A system for generating a periodic scanning current for a scanningWinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Winding portions and including a circuit for coupling a scanningvvinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit throughv afirst of said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current ina scanning Winding coupledthereto; a circuit including a rectier device and a second of saidwinding portions and cooperating with said electron-discharge device tocarry at least a portion of said scanning current; and a circuitincluding a unidirectional voltage source, a substantialalternating-current impedance, and a third of said winding portions forsupplying a direct component of current which includes the directcomponent of current of said output electrodes; said first windingportion being at least in part distinct from said third Winding portionand the product of the effective number of turns of said third Windingportion and said first-mentioned direct component of current being asubstantial fraction of the product of the effective number of turns ofsaid first Winding portion and said direct component of output electrodecurrent, and said third Winding portion being wound and connected insuch sense relative to said first winding portion that said direct-components of current have opposite directions relative to saidmagnetic core. Y

5. A system for generating a periodic scanning `current for a scanningwinding of a cathode-ray 16 tube comprising: a primarily inductive loadcir'- cuit including a transformer having a magnetic core and aplurality of Winding portions and including a circuitfor coupling ascanning Winding thereto; an electron-discharge device having inputelectrodes and having output electrodes coupled to said load circuitthrough a first of said Winding portions; a circuit for applying to saidinput electrodes a control voltage for periodically rendering saiddevice conductive to develop said scanning current in a scanning windingcoupled thereto; a circuit including a rectifier device and a second ofsaid winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; and acircuit including a unidirectional voltage source, a substantialalternating-current impedance, and a third of said winding portions forsupplying a direct component of current which' includes the directcomponent of current of said output electrodes; said first windingportion being at least in part distinct from said third Winding portionand the product of the effective number of turns of said third Windingportion and said rst-mentioned direct component of current being Withinthe range of `0.9 to 1 times4 the product of the effective number ofturns of said rst Winding portion and said direct component of outputelectrode current, and said third Winding portion being wound andconnected in such sense relative to said first Winding portion that saiddirect components of current have opposite directions relative to saidmagnetic core.

6. A system for generating a periodic scanning current for a scanningWinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and aplurality ofWinding portions and including a circuit for coupling a scanning Windingthereto; an electron-discharge device having input electrodes and havingoutput electrodes coupled to said load circuit through a nrstrof saidwinding portions; a circuit for applying to said input electrodes acontrol voltage for periodically rendering said device conductive todevelop said scanning current in a scanning winding coupled thereto; acircuit including a rectifier device and a second of said Windingportions and cooperating with said electron-discharge device to carry atleast a portion of said scanning current; and a circuit including aunidirectional voltage source, a substantial alternating-currentimpedance, and 'a third of said Winding portions for supplying a directcomponent of current which includes the direct component of current ofsaid output electrodes; said iirst Winding portion being at least inpart distinct from said third `Winding portion and the product of theeffective number of turns of said third Winding portion and saidfirst-mentioned direct cornponent of current and the product of theelective number of turns of said nrst winding portion and said directcomponent or^ output electrode current having a ratio of substantially9/10, and said third Winding portion being Wound and connected in suchsense relative to said rst winding portion that said direct componentsof current have opposite directions relative to said magnetic core.

7. A system for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including an autotransformer having a continuous winding, amagnetic core, and a plurality of winding portions *and including acircuit for coupling a scanning winding thereto,

said winding portions Ibeing at least in Vpart dis- Y tinct from oneanother; an electron-discharge device having Yinput electrodes andhaving output electrodes coupled to said load circuit through a first ofsaid winding portions; a circuit for applying to said input electrodes acontrol voltage for periodically rendering said Adevice conductive 'todevelop said scanning current `in a scanning Winding coupled thereto; a.circuit including a rectifier device and a second of said windingportions and cooperating with said electron-discharge device to .carryat least a portion of said scanning current; and a circuit including aunidirectional Yvoltage source, a substantial alternating-currentimpedance, and a third of said Winding portions for supplying a directcornponent of current which includes the direct component 'of current ofsaid output electrodes; said rst winding portion being at least in partdistinct from said third winding portion and the product of theeffective number of turns of said third winding portion and saidfirst-mentioned Winding portion that said direct components of currenthave opposite directions relative to said magnetic core.

8. A system for generating a periodic scanning current for a scanningwinding of Va cathoderay tube comprising: a primarily inductive loadcircuit including a transformer having a inagnetic core and a pluralityof winding portions and including a circuit for coupling a scanningwinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through afirst of said Winding portions; a circuit .for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning Windingcoupled thereto; a .circuit including .a rectier device and a second ofsaid winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; and acircuit including a unidirectional voltage source, an inductor, and athird of said Winding portions for supplying a direct component ofcurrent which includes the direct component of current of said outputelectrodes; said first Winding portion being at least in part distinctfrom said third Winding portion and the product of the effective numberof turns of said third winding portion and said first-mentioned directcomponent of current being approximately equal to the product of theeffective number of turns of said first Winding portion and said directcomponent of output electrode current, and said third Winding portionbeing Wound and connected in such sense relative to said first windingportion that said direct components of current have opposite directionsrelative to said `magnetic core.

9. A system for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a `pluralityof Winding portions and including a circuit for coupling a scanningwinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through a rstof said Winding portions; a circuit for applying to said inputelectrodes a control voltage .for periodically rendering said 'deviceconductive to develop said scanning current in a scanning Windingcoupled thereto; a circuit including a rectier device and a second ofsaid winding portions and cooperating with said electron-discharge.device to .carry at least a vportion of said Vscanning current; and acircuit including a unidirectional voltage source, a substantialalternating-current impedance, and athird of said Winding portions forsupplying a direct component of current which includes the .directcomponent of current of said output electrodes.; said first Windingportion effectively having .a greater number of turns than said thirdwinding portion and the product of the eii'ective number of turns ofsaid third Winding portion and said rst-nentioned direct component ofcurrent being approximately equal to the product of the eiiective numberor" turns of said iirst winding portion and said direct component ofoutput electrode current, and said third Winding portion vbeing Woundand connected in such sense relative to said iirst winding portion thatsaid direct components of .current have opposite directions relative tosaid magnetic core.

10. A system for generating a periodic scanning current for a scanninglWinding ofa cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Windingrportions and including a circuit for coupling a scanningWinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through a rstof said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductiveY to develop said scanning current in a-scanning Windingcoupled thereto; a circuit including a unidirectional voltage source, arectiiier devi-ce, a low-impedance condenser, and a second of saidWinding portions and cooperating with said electron-discharge device tocarry atleast a portion of said scanning current; and a circuitincluding said unidirectional voltage source, .said rectiiier device, asubstantial alternating-current impedance, and a third of said Windingportions for supplying a direct component oi current which includes thedirect component of .current of said output electrodes; said lirstWinding portion being at least in part distinct from said third Windingportion and the product of the eiiective number of turns of said .thirdWinding portion and said Erst-mentioned direct -component of currentbeing approximately equal to the product of the effective number ofturns of said first Winding portion and said direct component of outputelectrode current, and said third Winding portion being wound andconnected in such sense relative to said first winding lportion thatsaid direct components of current have opposite directions relative tovsaid magnetic core.

11. A system lfor generating a periodic scanning current for a scanningWinding oi' a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer Yhaving a magnetic Vcore and apluralityof winding portions and including a circuit for coupling a scanningwinding thereto; an lelectron--discharge device having input electrodesand having output electrodes coupled to said load circuit through afirst of said winding portions; a circuit 'for applying to said inputelectrodes a control voltage for periodically rendering said devi-ceconductive to develop said scanning current in a scanning windingcoupled thereto; a voltage-generating circuit including a unidirectionalvoltage source, a rectier device, a low-impedance condenser, and asecond of said Winding portions for developing a unidirectional voltagesubstantially higher than that of said source; and a circuit includingsaid unidirectional voltage source, a substantial alternating-currentimpedance, and a third of said Winding portions for supplying a directcomponent of current which includes the direct component of current ofsaid output electrodes; said rst Winding portion being at least in partdistinct from said third Winding portion and the product of theeffective number of turns of said third winding portion and saidfirst-mentioned direct component of current being approximately equal tothe product of the effective number of turns of said first Windingportion and said direct component of output electrode current, and saidthird Winding portion being wound and connected in such sense relativeto said i'lrst winding portion that said direct components of currenthave opposite directions relative to said magnetic core.

12. A system for generating a periodic scanning current for a scanningwinding of a cathoderay tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Winding portions and including a circuit for coupling a scanningwinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through a rstof said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning windingcoupled thereto; a voltage-generating circuit including a unidirectionalvoltage source, a rectier device, a low-impedance condenser, a second ofsaid Winding portions, and an energy-storage device for developingacross said energy-storage device a unidirectional voltage substantiallyhigher than that of said source; and a circuit including aunidirectional voltage source, a substantial alternating-currentimpedance, and a third of said Winding portions for supplying a directcomponent of current which includes the direct component of current ofsaid output electrodes; said nrst Winding portion being at least in partdistinct from said third winding portion and the product of theeffective number of turns of said third Winding portion and saidrst-mentioned direct component of current being approximately equal tothe product of the eifective number of turns of said rst Winding portionand said direct component of output electrode current, and said thirdWinding portion being Wound and connected in such sense relative to saidfirst Winding portion that said direct components of current haveopposite directions relative to said magnetic core.

13. A system for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Winding portions and including a circuit for coupling a scanningwinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through afirst of said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning Windingcoupled thereto; a voltage-generating circuit including a unidirectionalvoltage source, a rectiner device, a low-impedance condenser, a secondof said Winding portions and an energy-storage device for developingacross said energy-storage device a unidirectional voltage substantiallyhigher than that of said source; a direct-current output circuitconnected to said energy-storage device; and a circuit including saidunidirectional voltage source, said rectifier device, a substantialalternating-current impedance, and a third of said Winding portions forsupplying a direct component of current which includes the directcomponent of current of said output electrodes; said first Windingportion being at least in part distinct from said third Winding portionand the product of the effective number of turns of said third Windingportion and said first-mentioned direct component of current beingapproximately equal to the product of the effective number of turns ofsaid rst Winding portion and said direct component of output electrodecurrent, and said third Winding portion being Wound and connected insuch sense relative to said first Winding portion that said directcomponents of current have opposite directions relative to said magneticcore. l

14. A system for generating a periodic scanning current for a scanningwinding of a cathoderay tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Winding portions and including a circuit for coupling a scanningWinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through a rstof said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning Windingcoupled thereto; a circuit including a rectier device and a second ofsaid Winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; and acircuit including a unidirectional voltage source, a substantialalternating-current impedance, and a third of said Winding portionshaving a greater number of turns than said second Winding portion forsupplying a direct component of current which includes the directcomponent of current of said output electrodes; said first Windingportion being at least in part distinct from said third Winding portionand the product of the eifective number of turns of said third Windingportion and said rst-mentioned direct component of current beingapproximately equal to the product of the effective number of turns ofsaid first Winding portion and said direct component of output electrodecurrent, and said third winding portion being Wound and connected insuch sense relative to said rst winding portion that said directcomponents of current have opposite directions relative to said magneticcore'.

15. A system for generating a periodic scanning current for a scanningwinding'of a cathode-ray tube comprising: a primarily inductive loadcircuit including'a transformer having a magnetic core and a pluralityof winding portions and including a circuit for coupling a scanningWinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through a rstof said winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning windingcoupled thereto; a circuit including a rectifier device and a second ofsaid winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; and acircuit including a unidirectional voltage source, a substantialalterhating-current impedance, and a third of said winding portions forsupplying a direct component of current which includes the directcomponent of current of said output electrodes; said rst Winding portionbeing at least in part distinct from and having a greater number of.turns than said third Winding portion and the product of the eectivenumber of turns' ofV said third Winding portion and said rst-mentioneddirect component of current being approximately equal to the product ofthe efiective number of turns of said rst Winding portion and saiddirect component of output electrode current, and said third windingportion being wound and connected in such sense relative to said firstwinding portion that said direct components of currents have oppositedirections relative to said magnetic core.

16. A system for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof Winding portions and including a circuit for coupling a scanningWinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through afirst of said Winding portions; a circuit for applying to said inputelectrodes a control voltage for periodically rendering said deviceconductive to develop said scanning current in a scanning windinglcoupled thereto; a circuit including a rectier device and a second ofsaid winding portions and cooperating with said electron-dischargedevice to carry at least a portion of said scanning current; and acircuit including in series a unidirectional voltage source, asubstantial alternating-current impedance, and a third of said Windingportions for supplying through said third winding portion a. directcomponent of current which includes the direct component of current ofsaid output electrodes; said first winding portion being distinct fromsaid third Winding portion and the product of the eiiective number ofturns of said third winding portion and said first-mentioned directcomponent of current being approximately equal to the product of theeffective number of turns of said rst winding portion, and said directcomponent of output electrode current, and said third winding portionbeing wound and connected in such sense relative to said first Windingportion that said direct components of current have opposite directionsrelative to said magnetic core.

17. A sys-tem for generating a periodic scanning current for a scanningwinding of a cathode-ray tube comprising: a primarily inductive loadcircuit including a transformer having a magnetic core and a pluralityof winding portions and including a circuit for coupling a scanningvvinding thereto; an electron-discharge device having input electrodesand having output electrodes coupled to said load circuit through afirst of said Winding portions; a circuit for applying to said inputelectrodes a control volt- .age for periodically rendering said deviceconductive to develop said scanning current in a scanning Windingcoupled thereto; a circuit in- 22` cluding a rectiier` device and asecond of said Winding portions and cooperating with saidelectron-discharge device to carry at least a portion.

of said scanning current; and a circuit including a unidirectionalvoltage source, a substantial alternating-current impedance, and a thirdof said winding portions for supplying a direct component of currentwhich includes the direct component of current of said outputelectrodes; vsaid Winding portions being distinct from each other andthe product of the effective number of turns of said third windingportion and said iirstmentioned direct component of current beingapproximately equal to the product of the effective number of turns ofsaid first Winding portion and said direct component of output'electrode current, and said third winding portion being Wound andconnected in such sense relative to said iirst Winding portion that saiddirectcomponents of current have opposite directionsr relative to saidmagnetic core.

18.'A system for generating a periodic scanning' current for a scanningwinding of a cathoderay tube comprising: a primarily inductive loadcircuit including an autotransformer having a magnetic core and a seriesof' Winding terminals and including a circuit for coupling a scanningvwinding to two of said terminals; an electrondischarge device, havinginput electrodes and having output electrodes including an anode coupledto said load circuit through a rst and. a second of said terminals withsaid anode connected to said second terminal; a circuit forv applying tosaid input electrodes a control voltage for periodically rendering saiddevice conductive to develop said scanning current in a scanning windingcoupled thereto; a circuit including a unidirectional voltage source, arectifier device, and a low-impedance condenser coupled to a third ofsaid terminals intermediate said iirst and said second terminals andcooperating with said electron-discharge device to carry at least aportion of said scanning current; and, a circuit source, said rectifierdevice, and a. substantial alternating-curent impedance coupled to afourth of said terminals intermediate said second. and.'

said third terminals for supplying a direct com-` ponent of currentwhich includes the. direct component of current of said outputelectrodes.

19. A system for generating a periodic scanning current for a scanningWinding of a cathoderay tube comprising: a primarily inductive loadcircuit including an autotransformer having a magnetic core and a seriesof Winding terminals and including a circuit for coupling a scanningwinding to two of said terminals; an electrondischarge device, havinginput electrodes a-nd having output electrodes including an anode,coupled to said load circuit through a first and a second of saidterminals With said anode connected to said second terminal; a circuitfor applying to said input electrodes a control voltage for periodicallyrendering said device conductive v to developsaid scanning current in ascanning winding coupled thereto; a circuit including a unidirectionalvoltage source, a rectifier device, and a low-impedance condensercoupled to a third of said terminals intermediate said first and Saidsecond terminals and cooperating with said electron-discharge device tocarry at least a portion of said scanning current; and a circuitincluding said unidirectional voltage source, said rectifier device,andan nductor coupled to a fourth of said terminals intermediate saidsecond including said unidirectional voltagev and said third terminalsfor supplying a direct component of current Which includes the directcomponent of current of said output electrodes. 20. A system forgenerating a periodic scanning current for a scanning Winding of acathode-ray tube comprising: a primarily inductive load circuitincluding an autotransformer having a magnetic core and a continuousWinding having a plurality of winding portions with a series of windingterminals and including a circuit for coupling a scanning Winding to tWoof said terminals; an electron-discharge device, having input electrodesand having output electrodes including an anode, coupled to said loadcircuit through a rst and a second of said terminals for a 'lirst ofsaid Winding portions with said anode connected to said second terminal;a circuit for applying to said input electrodes a control voltage forperiodically rendering said device conductive to develop said scanningcurrent in a scanning Winding coupled thereto; a circuit including aunidirectional voltage source, a rectier device, and a 10W-impedancecondenser coupled to a third of said terminals for a second of saidWinding portions intermediate said first and said second terminals andcooperating with said electron-discharge device to carry at least aportion of said scanning current; and a circuit including saidunidirectional voltage source, said rectier device, and a substantialalternatingcurrent impedance coupled to a third of said Winding portionswith a fourth of said terminals intermediate said second and said thirdterminals for supplying a direct component of current Which includes thedirect component of current of said output electrodes; said firstwinding portion being at least in part distinct from said third Windingportion and the product of the effective number of turns of said thirdwinding portion and said rst-mentioned direct component of current beingapproximately equal to the product of the effective number of turns ofsaid rst Winding portion and said direct component of output electrodecurrent, and said third Winding portion being Wound and connected insuch sense relative to said first Winding portion that said directcomponents of current have opposite directions relative to said magneticcore.

21. A system for generating a periodic scanning current for a scanningWinding of a cath- Y ode-ray tubey comprising: a primarily inductiveload circuit including an autotransformer having a ferromagnetic coreand a series of Winding terminals and including a circuit for coupling ascanning Winding to two of said terminals; an electron-discharge device,having input electrodes and having output electrodes including an anode,coupled to said load circuit through a first and a second of saidterminals with said anode connected to said second terminal; a circuitfor applying to said input electrodes a control voltage for periodicallyrendering said device conductiveto develop said scanning current in ascanf ning winding coupled thereto; a circuit including a unidirectionalvoltage source, a rectifier device, and a low-impedance condensercoupled to a third of said terminals intermediate said first and saidsecond terminals and cooperating with said electron-discharge device tocarry at least a portion of said scanning current; and a circuitincluding said unidirectional voltage source, said rectifier device, anda substantial alternatingcurrent/impedance coupled to a fourth of saidterminals intermediate said second and said third terminals forysupplying a direct component of current which includes the directcomponent of current of said output electrodes; said condenser and saidalternating-current impedance being so proportioned that the currentflowing through said condenser builds up across said condenser a voltagewhich is impressed on said scanning Winding after transformation andwhich at least in part compensates vfor nonlinearity i-n the scanning ofa cathode-ray tube.

ALAN HAZELTINE.

References Cited in the le of this patent UNITED STATES PATE-NTS NumberName Date 2,536,839 Clark et al. Jan. 2, 1951 2,536,857 Schade Jan. 2,1951 2,543,719 Clark Feb. 27, 1951 2,543,720 Hoyt Feb. 27, 19512,566,510 Barco Sept. 4, 1951 2,588,659 Pond Mar. l1, 1952 2,611,106Fyler et al Sept. 16, 1952

